My dad would say: "Take half the stuff and twice as much money. . ."
You don't mention a daily budget, but I'm guessing it's bare bones (been there, if fact, I toured the west coast back in the 80s because I couldn't even afford airfare to Europe). I'd think twice on ground cloth and tarp -- you can let your hammock serve as a bivvy and call it done, especially if you're into hostels. They in turn will want you to have a sleep sack in all probability. You can rent them there or buy one when you get there. I was never hassled when rogue camping so the camo net is optional. Pick your place carefully instead.
If you're camping frequently, you might want to buy batteries as you go for your camera since power will be scarce. Your Swiss Army knife has a nice opener. I never really cooked anything. If you can get by on deli type food (and Europe is THE place for that kind of eating) you probably don't need a stove or pot, etc. Most folks there grocery shop every day, just like you'll be doing. The stores are set up for small purchases of hot and cold dishes.
The advice on packing for a week being the same as for longer is right on. My wife and I just finished a 6 week trip through Europe and packed, essentially, for 3 days. You just wash as you go. To that end, a sink stopper may be something that you need to pick up. Also, there's a soap called Dr. Bronner's that some say works for all uses (except toothpaste). I haven't tried it, so I can't vouch for it.
If you haven't yet, check out Rick Steve's website. He's something of a "European Travel Guru" here in the states, he's out of the Seattle area.
There's nothing on your list that you can't get there if you need it. By the same token, it's a snap to mail stuff back to yourself if find you don't need it.
Good luck and have fun. . . and if figuratively you ever find the roads are all uphill, cobblestoned and there's 50km headwind blowing cold rain at you, remember we're with you in spirit, and eventually, you'll hit the downhill part!